In regards to bitcoin, Peter Todd says: "Fundamentally the tech itself does not scale. The whole idea of everyone knowing everything about every transaction, which is inherent to the trust model of bitcoin right now... that's simple: O(n^2) scaling. You just can't get away from that. No matter how much you push and pull that constant k value, you'll never get away from the fact that fundamentally it's O(n^2) scaling.
I assume n represents number of transactions? What does k represent?
Also, is Peter referring to "Load" scalability? (wikipedia: The ability for a distributed system to easily expand and contract its resource pool to accommodate heavier or lighter loads or number of inputs. Alternatively, the ease with which a system or component can be modified, added, or removed, to accommodate changing load.)